The COVID-19 pandemic continues to endanger world health and the economy. The causative SARS-CoV-2 coronavirus has a unique replication system. The end point of the COVID-19 pandemic is either herd immunity or widespread availability of an effective vaccine. Multiple candidate vaccines – peptide, virus-like particle, viral vectors (replicating and nonreplicating), nucleic acids (DNA or RNA), live attenuated virus, recombinant designed proteins and inactivated virus – are presently under various stages of expansion, and a small number of vaccine candidates have progressed into clinical phases. At the time of writing, three major pharmaceutical companies, namely Pfizer and Moderna, have their vaccines under mass production and administered to the public. This review aims to investigate the most critical vaccines developed for COVID-19 to date.

Our study reports greener synthesis of gold nanoparticles (AuNPs) tethered to the extract of Croton sparsiflorus and in vitro evaluation of UV‐protection, antibacterial and anticancer activities. Sophisticated instrumental analytical techniques such as UV–vis spectrophotometer, FT‐IR, XRD, FE‐SEM, and TEM were employed for the existence and confirmation of the nanoparticles. FT‐IR and HPLC analysis were executed in the identification of the plausible functional groups implicated in the reduction of gold ions to AuNPs. UV protection property and antibacterial action of AuNPs‐coated cotton fabric were also presented. Moreover, in vitro anticancer evaluation against HepG2 cell line was conducted by MTT assay for Croton sparsiflorus extract derived AuNPs in different concentrations (50 to 150 μg/ml). Thus, the results of this work revealed that greener synthesized AuNPs exhibited good therapeutic applications as UV‐protection, antibacterial and anticancer agents.

This study was aimed at developing a simple, eco-friendly and cost effective green chemistry method for the synthesis of bimetallic Au-Ag nanoparticles using Ocimum basilicum aqueous leaf and flower extracts, respectively as the natural reducing agents. The successive reduction of chloroauric acid and silver nitrate led to the formation of Au-Ag nanoparticles within 10 min at room temperature, suggesting a higher reaction rate than chemical methods involved in the synthesis. Stable, spherical nanoparticles with well-defined dimensions of average size of 3-25 nm was confirmed by UV-Visible spectroscopy, TEM, SEM-EDX, DLS, and zeta potential, whilst, FTIR in combination with GC-MS analyzed the functional groups adhered to the surface of the nanoparticles. The colloidal suspension displayed enhanced antihyperglycemic activity at 69.97 ± 3.42% (leaf) against α-amylase (from porcine) and at 85.77 ± 5.82% (flower) against Bacillus stearothermophilus α-glucosidase than that of acarbose and their respective crude extracts. Furthermore, revealed good antibacterial activity against bacterial species Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa.